Fine mapping and interaction analysis of a linear rabies virus neutralizing epitope

Area of Science:

• Virology
• Immunology
• Structural Biology

Background:

• Rabies virus glycoprotein (RVG) is a key target for neutralizing antibodies.
• Developing potent and broadly neutralizing antibodies is crucial for rabies prevention.

Purpose of the Study:

• To characterize the novel human antibody AR16 targeting the G5 epitope of RVG.
• To identify the minimal binding region and key residues involved in AR16-RVG interaction.
• To evaluate the potential of an AR16-based antibody cocktail for broad rabies virus neutralization.

Main Methods:

• Epitope mapping using antibody AR16 to identify the minimal binding region (HDFR) and key residues (HDF) on RVG.
• Alanine replacement scanning to confirm key residues.
• Bioinformatic analysis of residue conservation across Lyssavirus phylogroups.
• Computer-aided docking and interaction modeling to elucidate antibody-epitope binding interfaces and forces.
• Analysis of antibody heavy chain variable regions.

Main Results:

• The minimal binding region of RVG targeted by AR16 was identified as HDFR (residues 261-264), with HDF (residues 261-263) being critical.
• The HDF epitope is conserved in phylogroup I Lyssaviruses but not phylogroup II.
• Key interacting residues of AR16 (Asp30, Asp31, Tyr32, Trp53, Asn54, Glu99, Ile101, Trp166) and mediating van der Waals forces were identified.
• Seven of the eight key AR16 residues are located in the heavy chain variable regions.
• A novel monoclonal antibody (mAb) cocktail of AR16 and CR57 demonstrated potential for broad rabies virus neutralization.

Conclusions:

• Antibody AR16 effectively targets a conserved epitope on rabies virus glycoprotein, providing significant antiviral potency.
• Understanding the molecular interactions between AR16 and its epitope aids in rational antibody design.
• A combination therapy using AR16 and CR57 offers a promising strategy for broad-spectrum rabies virus neutralization.